Method for Producing Glucosamine by Culturing Microorganism with Low-cost Medium

ABSTRACT

A method for producing glucosamine with microorganism comprises of fermenting with a microorganism selected from the group consisting of  Monascus pilosus  and  Aspergillus  sp. in a novel low-cost medium, thereby enable it to produce glucosamine; wherein said medium is consisted of commercial Taiwan sugar, soy beam, rice bran and the like; wherein suitable condition for the fermentation is: 150˜300 rpm, pH 4˜pH 8, and 24° C.˜37° C.; wherein, after fermentation culturing, the fermentation liquor is filtered with suction to recover said microorganism biomass, said microorganism biomass is then subjected to steps of cell disruption, hydrochloric acid reaction, neutralization reaction and filtration, to obtain glucosamine produced by the microorganism.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser. No. 12/407,171 filed on Mar. 19, 2009, which is incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for producing glucosamine by culturing microorganism with a novel low-cost medium.

2. Description of the Prior Art

Glucosamine is one of the constitutional ingredients for articular cartilage, which can provide nutrition for articular tissue, enhancing the ability of synovial fluid for recovering lubricating function, promote the regeneration of retrograded joints, and hence reduce effectively the pain generated from bone friction, as well as prevent the aggravation of arthritis condition. Glucosamine can be synthesized by human body itself. However, as age increased, the synthesis speed for glucosamine in the human body is lower than that of the decomposition speed of glucosamine, and consequently, the body and joints tend to be short of glucosamine, and further, the metabolism of cells in joints may be affected.

The feature of glucosamine comprises: (1) stimulating the regeneration of chondroblast, promoting metabolism thereof, supplying nutrition for bone, reducing inflammation, and vanishing paint; (2) protecting cartilage cells from damage by drugs and external force, and preventing degeneration of joint; (3) increasing the amount of synovial fluid and viscosity thereof, enhancing the lubrication effect of the joint, and improving the function of the joint; (4) ameliorating sore waist and backache. Furthermore, in Europe, glucosamine has been used widely in treating osteo-arthritis. Once administrated, glucosamine can be absorbed fast, delivered to and used by various tissues in the body. The rate acute toxicity assay and microorganism mutagenicity study had shown that glucosamine is a safe and nontoxic health product, and earlier supplement of glucosamine can give an effect of preventing arthritis.

Glucosamine may be obtained naturally by extracting from chitin in carapace of marine shrimp and crab, as well as by chemical synthesis. At present, industrial production of glucosamine is carried out still by hydrolyzing the carapace of shrimp and crab in hydrochloric acid solution. Conventional method for producing glucosamine comprises of hydrolyzing chitin with acid or enzymes. However, shrimp and crab carapaces obtained from different sources may affect the purity of glucosamine. In addition, glucosamine produced form contaminated shrimp and crab carapaces may be toxic. Furthermore, before hydrolyzing the shrimp and crab carapaces, rinsing of these carapaces should be carried out with much time and work to prevent notorious stinks. Moreover, glucosamine is not the only one product in the hydrolyzing product of those carapaces, and additional purification steps are needed to perform in order to isolate glucosamine and other by-products. In the consideration of reducing those tedious pre-treatment steps and diminishing allergic side effect sequela after taking up in the human body, microorganism producing approached had been suggested in lieu of conventional chemical method.

In addition to the above-described hydrolysis method, two methods for producing glucosamine from microorganism are used currently. One of these consists of decomposing chitin by means of intracellular and extracellular enzymes of fungus, while the other method consists of converting primary metabolism medium for microorganism into secondary metabolism medium, for producing glucosamine from that medium.

Study of Deng et al in 2005 pointed out that currently, gene transfer technique had been used to produce glucosamine-producing Escherichia coli. Unfortunately, since the regulatory mechanism involved was too complicated such that the detectable amount of glucosamine in the medium for E. coli became extremely low, only several milligram per liter. E. coli produced by gene transfer technology could increase the yield of amino-sugars. Said gene transfer strategy involved the promotion of genes associated with the function and catabolism of glucosamine, as well as the overexpression of the glucosamine synthase gene. Said method could increase up to 15-times of the glucosamine yield, but its titer remained still at the level of milligram. Feedback inhibition of glucosamine synthase had been identified to be a critical factor for that route. Further, screening of enzymes might increase the production of glucosamine, and could increase its titer to the level of several grams. Unfortunately, fast degradation of glucosamine in host cell, inhibition effect of glucosamine and degradation product thereof might hinder the increase of the glucosamine concentration [Deng, Ming-de, K. D. Severson, D. A. Grund, S. L. Wassink, R. P. Burlingame, A. Berry, J. A. Running, C. A. Kunesh, L. Song, T. A. Jerrell and R. A. Rosson, From Conceptto Process: Metabolic Engineering for Production of Glucosamine and N-Acetylglucosamine, Metabolic Engineering, 7(3), 201-214 (2005)].

In conventional technique and literature, study aimed at producing glucosamine by way of secondary metabolites of microorganism is neither much nor comprehensive, but only following few fungi has been mentioned to contain glucosamine in their secondary metabolites:

1. Monasus: Most of the attention had been focused on contents monacolin K and GABA, far less on the fact that Monasus contained glucosamine. Hsieh et al. pointed out in their study in 2007 that in a medium consisting of 20 g/L rice bran, 25 g/L B-grade white crystal sugar, 15 g/L ammonium chloride, Monascus pilosus could produce 0.72 g/dm³ of glucosamine, with its optimal condition as: pH 5, and 30° C. [Hsieh, J. W., H. S. Wu, Y. H. Wei, and S. S. Wang, Determination and kinetics of producing glucosamine using fungi, Biotechnol. Prog., 23, 1009-1016 (2007)].

2. Aspergillus: Aspergillus is a filamentous fungus widely present in nature world. Many Aspergillus fungi may produce secondary metabolites harmful to human body. Among them, the most well-known one is aflatoxin produced by Aspergillus flavus and Aspergillus parasiticus. Aflatoxin had been identified as a carcinogenic substance. Nevertheless, Hsieh et al. had indicated in their study in 2007 that, in a certain medium, Aspergillus sp. could produce 3.43 g/dm³ of glucosamine, with optimal condition as: pH 7 and 30° C. [Hsieh, J. W., H. S. Wu, Y. H. Wei, and S. S. Wang, Determination and kinetics of producing glucosamine using fungi, Biotechnol. Prog., 23, 1009-1016 (2007)].

In view of the foregoing, conventional methods for producing glucosamine have still many disadvantages, and among the other, the production of glucosamine from microorganism fails to increase greatly as well as the cost of the medium is impossible to cut down, and consequently, are not well-designed and needs improvement urgently.

The inventors had learned various disadvantages derived from the above-described conventional methods for producing glucosamine, and devoted to improve and innovate, and finally, after studying intensively for many years, has developed successfully a method for producing glucosamine by culturing microorganism with low-cost medium.

SUMMARY OF THE INVENTION

One object of the invention is to provide a method for producing glucosamine by culturing microorganism with low-cost medium, characterized in that it is a method comprised of developing a novel low-cost medium for culturing microorganism, and producing glucosamine through fermentation, thereby replaces conventional medium, and cuts down the cost of the medium.

Another object of the invention is to provide a method for producing glucosamine by culturing microorganism with low-cost medium, by using first a manner of shaking-flask culturing, and then going through fermentation mode to carry out optimization study for the production of glucosamine; and further, fermenting with a fermenter to produce glucosamine, in order to increase the production of glucosamine by microorganism.

The method for producing glucosamine by culturing microorganism with low-cost medium that can achieve the above-mentioned objects of the invention is a method for producing glucosamine by culturing a suitable microorganism with a medium consisting of Taiwan sugars, soy beam, and rice bran, comprises fermenting under suitable conditions, a suitable microorganism selected from the group consisting of Monascus pilosus and Aspergillus sp., thereby enabling them to produce glucosamine.

The term “suitable microorganism” means the microorganism can be produced glucosamine under appropriate culture condition in this invention.

wherein said Monascus pilosus and Aspergillus sp. were general usage bacterium strain. Also, they were both commercial available. The source of suitable microorganism includes, but not limited to: Monascus pilosus BCRC31527, with an accession number corresponding to ATCC 22080, and Aspergillus sp. BCRC31742, with an accession number corresponding to UPCC 3868. Both of the above-mentioned strains could be purchased from Food Industry Development and Research Institute, Hsin-chu, Taiwan, ROC, ATCC, UPCC, or other suitable commercial company. In one preferred embodiment of the invention, said microorganism is preferably Aspergillus sp. BCRC 31742.

In one preferred embodiment of the invention, said microorganism Monascus pilosus BCRC 31527 is cultured by fermenting in a RBA liquid medium; said RBA liquid medium is consisted of 25 g/L rice bran, 25 g/L B-grade white crystal sugar and 15 g/L NH₄Cl.

In one preferred embodiment of the invention, said microorganism Monascus pilosus BCRC 31527 is fermented under stirring at 150˜300 rpm, preferably at 150˜250 rpm, and most preferably at 200 rpm. In one preferred embodiment of the invention, said microorganism is fermented at pH 4˜pH 6, preferably at pH 4.5˜pH 5.5, and most preferably at pH 5. In one preferred embodiment of the invention, said microorganism is fermented at 24° C.˜37° C., preferably at 28° C.˜33° C., and most preferably at 30° C.

In one preferred embodiment of the invention, said microorganism Aspergillus sp. BCRC 31742 is cultured separately in WP, WS or WPS liquid media; wherein said WP liquid medium is consisted of suitable concentration of Superior white fine granulated sugar, suitable concentration of Peptone, 0.5 g/L KH₂PO₄, 0.5 g/L MgSO₄.7H₂O and 0.1 g/L CaCl₂.2H₂O; a preferred WP liquid medium (WP1) is consisted of 25 g/L Superior white fine granulated sugar, 20 g/L Peptone, 0.5 g/L KH₂PO₄, 0.5 g/L MgSO₄.7H₂O and 0.1 g/L CaCl₂.2H₂O; the most preferably WP liquid medium (WP2) is consisted of 33.9 g/L Superior white fine granulated sugar, 40.6 g/L Peptone, 0.5 g/L KH₂PO₄, 0.5 g/L MgSO₄.7H₂O and 0.1 g/L CaCl₂.2H₂O; wherein said WS liquid medium is consisted of suitable concentration of Superior white fine granulated sugar, suitable concentration of Soy bean meal or Soy bean, 0.5 g/L KH₂PO₄, 0.5 g/L MgSO₄.7H₂O and 0.1 g/L CaCl₂.2H₂O; a preferred WS liquid medium (WS1) is consisted of 25 g/L Superior white fine granulated sugar, 50 g/L Soy bean meal, 0.5 g/L KH₂PO₄, 0.5 g/L MgSO₄.7H₂O and 0.1 g/L CaCl₂.2H₂O; a preferred WS liquid medium (WS2) is consisted of 25 g/L Superior white fine granulated sugar, 20 g/L Soy bean, 0.5 g/L KH₂PO₄, 0.5 g/L MgSO₄.7H₂O and 0.1 g/L CaCl₂.2H₂O; wherein said WPS liquid medium is consisted of suitable concentration of Superior white fine granulated sugar, suitable concentration of Peptone, suitable concentration of Soy bean, 0.5 g/L KH₂PO₄, 0.5 g/L MgSO₄.7H₂O and 0.1 g/L CaCl₂.2H₂O; a preferred WPS liquid medium (WPS1) is consisted of 25 g/L Superior white fine granulated sugar, 10 g/L Peptone, 23 g/L Soy bean, 0.5 g/L KH₂PO₄, 0.5 g/L MgSO₄.7H₂O and 0.1 g/L CaCl₂.2H₂O; a preferred WPS liquid medium (WPS2) is consisted of 25 g/L Superior white fine granulated sugar, 40 g/L Peptone, 46 g/L Soy bean, 0.5 g/L KH₂PO₄, 0.5 g/L MgSO₄.7H₂O and 0.1 g/L CaCl₂.2H₂O.

In one preferred embodiment of the invention, said microorganism Aspergillus sp. BCRC 31742 is fermented under stirring at 150˜300 rpm, preferably at 150˜250 rpm, and most preferably at 200 rpm; said microorganism is fermented at pH 6˜pH 8, preferably at pH 6.5˜pH 7.5, and most preferably at pH 7; said microorganism is fermented at 24° C.˜37° C., preferably at 28° C.˜33° C., and most preferably at 30° C.

In one preferred embodiment of the invention, after culturing said microorganism by fermentation, the fermentation liquor is filtered with suction to collect biomass of said microorganism, and said biomass of microorganism is subjected to a process comprising steps of cell disruption, acidification with hydrochloric acid, neutralization and filtering, to obtain glucosamine produced by said microorganism; wherein in said acidification step, 1 g of wet biomass is acidified with 6N HCl at 100° C. for 4 hours, to gain a glucosamine concentration approaching an stationary value; and wherein said neutralization reaction is carried out with NaOH to pH 7.

These features and advantages of the present invention will be fully understood and appreciated from the following detailed description and will be illustrated with following non-limiting examples.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Example 1 Test Medium 1. Experimental Strains

The invention discloses a method for producing glucosamine by fermenting a non-gene-transferred microorganism with changing medium. The microorganism used was one of the following: Monascus pilosus BCRC31527, with an accession number corresponding to ATCC 22080, and Aspergillus sp. BCRC31742, with an accession number corresponding to UPCC 3868. Both of the above-mentioned strains were purchased from Food Industry Development and Research Institute, Hsin-chu, Taiwan, ROC.

2. Medium

An appropriate medium was selected based the different characteristics of the above-mentioned two strains for carrying out the production of glucosamine. Media selected for each of the two strains were listed in Table 1.

TABLE 1 Media for various glucosamine-producing strains Components Concentration Strain Medium in medium (g/L) Monascus RBA (pH 5) Rice bran 25 pilosus B-grade white 25 BCRC31527 crystal sugar NH₄Cl 15 Aspergillus sp. WP1 (pH 7) Superior white fine BCRC31742 granulated sugar 25 Peptone 20 Basic media WP2 (pH 7) Superior white fine granulated sugar 33.9 Peptone 40.6 Basic media Aspergillus sp. WS1 (pH 7) Superior white fine BCRC31742 granulated sugar 25 Soy bean meal 50 Basic media WS2 (pH 7) Superior white fine granulated sugar 25 Soy bean 20 Basic media WPS1 (pH 7) Superior white fine granulated sugar 25 Peptone 10 Soy bean 23 Basic media WPS2 (pH 7) Superior white fine granulated sugar 25 Peptone 40 Soy bean 46 Basic media Following constituents are commercially available:

-   RBA: Rice bran (commercial product)+B-grade white crystal sugar     (TSC, Taiwan)+Ammonium chloride (NH₄Cl, R.D.H., Germany). -   WP: Superior white fine granulated sugar+Peptone+Basic media. -   WS: Superior white fine granulated sugar+Soy bean (commercial     product)+Basic media. -   WPS: Superior white fine granulated sugar+Peptone+Soy bean+Basic     media. -   Basic media: 0.5 g/L KH₂PO₄+0.5 g/L MgSO₄.7H₂O+0.1 g/L CaCl₂.2H₂O. -   WS1: Wherein soy bean meal was ground into powder and 50 g/L of said     soy bean meal was added in medium. -   WS2: 20 g/L soy bean (not ground) was added in medium. -   WPS1 and WPS2: Soy bean was milled into powder and suspended     homogeneously in distilled water, most of the dregs were filtered     off with filtering cloth, and the filtrate was added in medium,     where its concentration was determined by calculating the weight     difference.

Example 2 Shaking-Flask Fermentation Test

Various strains described in Example 1 was activated separately through three region streak plate culturing in PDA solid medium (Potato Dextrose Agar: 200 g/L Diced potatoes, 20 g/L Glucose, 15 g/L Agar) at 30° C. for 5 days. Then, single colony was picked up and placed in 200 cm³ sterilized PDB liquid medium (Potato Dextrose Broth: 20 g/L Diced potatoes, 4 g/L Glucose) contained in a 250-cm³ shaking-flask, followed by secondary activation through incubating in a thermostatic incubator at 30° C. and 200 rpm for 7 days.

Stains thus-activated was used to inoculate in a suitable medium (Table 1), and the pH of the medium was controlled as followed: pH of the medium used for microorganism Monascus pilosus BCRC 31527 was pH 5, pH of the medium used for microorganism Aspergillus sp. BCRC 31742 was pH 7. Thereafter they were incubated at a temperature of 30° C., and 200 rpm for 7 days. Samples were taken and the cell dry weight and yield of glucosamine were determined as followed: the fermentation liquor of Monascus pilosus BCRC31527 was poured in a 250-cm³ centrifuge flask and centrifuged at 4° C. and 12,000 rpm for 30 min; the supernatant was decanted, the bacteria pellet was dried in an oven at 100° C., and the cell dry weight was determined (cell dry weight). Further, the pellet was pulverized, 10 cm³ of 6N HCl was added thereto and the mixture was reacted at 100° C. for 24 hours to obtain solution containing glucosamine. Separately, aliquot of fermentation liquor of Aspergillus sp. BCRC31742 was dried with suction to obtain a bacteria cake. A sample of the cake was dried in an oven at 100° C., and ratio of wet cell weight to dry cell weight was determined. Furthermore, wet bacteria was disrupted in a cell disrupter, 10 cm³ 6N HCl was added thereto and the mixture was reacted at 100° C. for 4 hours to obtain a solution containing glucosamine. After cooling down of the solution thus-collected, 10 cm³ of ultrapure water was added thereto, and the resulted solution was neutralized with NaOH to pH 7, and then a filtrate was collected by filtering with suction. Thereafter, 0.1 cm³ of the filtrate was placed in a test tube, 0.1 cm³ of a solution of 3,5-dinitrobenzonitrile in acetonitrile was added and used as an internal standard, and 0.1 cm³ of 40 mol/m³ solution of 1-naphthyl isothiocyanate in pyridine was added, followed by reacting in a thermostatic water bath at 50° C. for 1 hour. After the reaction, an aliquot of 10 μL was subjected to identification and analysis of glucosamine.

High Performance Liquid Chromatography (HPLC) was used to identify and analyze glucosamine. Analytical conditions for HPLC were as followed:

HPLC pump: Shimadzu LC-10AS

Detector: Shimadzu Model SPD-10Avp UV-VIS index detector

Column: LichroCART RP-18 (5 μm), 250×4 mm I.D.

Mobile phase: Water/Acetonitrile (87/13)

Flow rate: 1.3 cm³/min

UV detecting wavelength: 230 nm

The peak area ratio of glucosamine hydrochloride to the internal standard was substituted in the glucosamine hydrochloride calibration curve of the peak area ration of glucosamine hydrochloride to the internal standard to obtain grams of glucosamine by intrapolation method, and converted to glucosamine concentration, glucosamine content), and its yield by converting to carbon source used in the fermentation culturing, and finally, converted against working days to obtain productivity. These results were shown in Table 2.

TABLE 2 Reference (boldface) and glucosamine concentration, glucosamine content, productivity and costs of medium for various strains in shaking-flask culturing Glucosamine Cost of Glucosamine content medium Biomass Yield concentration (g/g- Productivity (USD/g- Strain medium (g/dm³) (g/g-C) (g/dm³) biomass) (g/dm³ · h) glucosamine) Reference Mo-31527 RBA 53.4 0.09 2.33 0.05 8.5 0.42 Mo RSA 17.7 0.04 0.72 0.04 4.28 3.33 1 As-31742 WP1 17.9 0.14 3.54 0.20 21.1 0.46 WP2 21.6 0.22 5.48 0.25 32.6 0.59 WS1 39.3 0.09 2.35 0.06 14.0 0.05 WS2 22.2 0.09 2.35 0.11 14.0 0.04 WPS1 24.2 0.13 3.31 0.14 19.7 0.27 WPS2 21.6 0.22 5.41 0.12 32.2 0.60 As GP 18.5 0.14 3.43 0.19 20.4 0.80 1 RBA: Rice bran, 0.4 USD/Kg; B-grade white crystal sugar, 0.97 USD/Kg; Ammonium chloride, 55 USD/Kg. RSA: Rice bran, 0.4 USD/Kg; Sucrose, 88.8 USD/Kg; Ammonium chloride, 55 USD/Kg. WP1, WP2, WS1, WS2, WPS1, WPS2: Superior white fine granulated sugar, 0.97 USD/Kg; Peptone, 78 USD/Kg; Soy bean, 1.3 USD/Kg; MgSO₄•7H₂O, 52 USD/Kg; KH₂PO₄, 39 USD/Kg; CaCl₂•7H₂O, 45.5 USD/Kg. GP: Glucose, 45.8 USD/Kg; Peptone, 78 USD/Kg; MgSO₄•7H₂O, 52 USD/Kg; KH₂PO₄, 39 USD/Kg; CaCl₂•7H₂O, 45.5 USD/Kg. Mo-31527: Monascus pilosus BCRC 31527; Mo: Monascus pilosus BCRC 31527 (reference 1); As-31742: Aspergillus sp. BCRC 31742; As: Aspergillus sp. BCRC 31742 (reference 1). Reference 1: Hsieh, J. W., H. S. Wu, Y. H. Wei, and S. S. Wang, Determination and kinetics of producing glucosamine using fungi, Biotechnol. Prog., 23, 1009-1016 (2007)

As shown in Table 2, between two strains used in this example, Aspergillus sp. BCRC 31742 cultured in WP2 medium could produce highest glucosamine concentration (5.48 g/dm³). When cultured in WS2 medium, the cost of the medium used to produce glucosamine was the least (0.04 USD/g-glucosamine). Further, as this example cultured culturing Aspergillus sp. BCRC 31742 or Monascus pilosus BCRC31527 under the condition using the inventive novel medium, Aspergillus sp. BCRC 31742 or Monascus pilosus BCRC31527 could produce more glucosamine, and the cost of the medium used was far cheaper compared with those described in reference 1.

Example 3 Fermentation Test in Fermenter

In this example, at first, Aspergillus sp. BCRC 31742 described in Example 1 was subjected to secondary activation culturing in accordance with the manner as in Example 2. Then, a fermentation test was carried out in a batchwise stirring fermenter as described below. The 100 cm³ thus-activated Aspergillus sp. BCRC 31742 liquor was inoculated in WP1 medium wothin the fermenter, and with a operation volume of 2 dm³, its was subjected to fermentation culture under optimal conditions obtained from shaking-flask experiment: pH 7, a temperature of 30° C., a rotational speed of 200 rpm, and with pure oxygen introduced through external lines to control the dissolved oxygen concentration at 10%.

After recovered from the fermenter, the fermentation liquor was filtered with suction to yield bacterial cake. Next, a sample of the bacteria cake was dried at 100° C., and the ratio of wet cell weight to dry cell weight was determined. Separately, wet cells were disrupted in a cell disrupter, 10 cm³ 6N HCl was added thereto and the mixture was reacted at 100° C. for 4 hours to obtain a liquid containing glucosamine. After cooling down, 10 cm³ ultrapure water was added, the reaction mixture was neutralized with NaOH to pH 7, and then the reaction mixture was filtered with suction to collect the filtrate. An aliquot of 0.1 cm³ was placed in a test tube, 0.1 cm³ solution of 3,5-dinitrobenzonitrile in acetonitrile was added and used as an internal standard, 0.1 cm³ of 40 mol/m³ solution of 1-naphthyl isothiocyanate in pyridine was added, and the mixture was allowed to react in a constant temperature water bath at 50° C. for 1 hour. After the reaction, an aliquot of 10 μL was subjected to identification and analysis of glucosamin. The same HPLC was carried out to identify and analyze glucosamine. The analytical conditions for HPLC was described as in Example 2.

The peak area ratio of glucosamine hydrochloride to the internal standard was substituted in the glucosamine hydrochloride calibration curve of the peak area ration of glucosamine hydrochloride to the internal standard to obtain grams of glucosamine by intrapolation method, and converted to glucosamine concentration, glucosamine content), and its yield by converting to carbon source used in the fermentation culturing, and finally, converted against working days to obtain productivity. These results were shown in Table 3.

TABLE 3 Reference (boldface) and glucosamine concentration, glucosamine content, yield and productivity obtained in fermenter culturing of Aspergillus sp. BCRC 31742 described in example 3. Yield Glucosamine Glucosamine Dissolved Biomass (g/g-carbon concentration content Productivity oxygen (g/dm³) source) (g/dm³) (g/g-biomass) (g/dm³ · h) Reference none 14.2 0.04 1.07 0.08 6.00  5% 13.7 0.05 1.25 0.09 7.44 10% 14.6 0.16 3.91 0.27 23.3 15% 11.1 0.13 3.34 0.30 13.8 20% 15.2 0.14 3.51 0.23 20.9 40% 15.5 0.13 3.18 0.21 18.9 60% 13.0 0.10 2.46 0.19 14.6 60% 10.0 0.09 2.31 0.23 13.7 1 Reference 1: Hsieh, J. W., H. S. Wu, Y. H. Wei, and S. S. Wang, Determination and kinetics of producing glucosamine using fungi, Biotechnol. Prog., 23, 1009-1016 (2007)

As shown in Table 3, conditions for fermenting Aspergillus sp. BCRC 31742 to produce glucosamine described in reference 1 was compared with those used in this Example. When result obtained by culturing Aspergillus sp. With GP medium to produce glucosamine as described by Hsieh et al. in 2007 (glucosamine concentration was 2.31 g/dm³) is compared with the result obtained by using the medium described in this example, it is seen that under identical microorganism fermentation conditions, WP medium used in this Example produced a glucosamine concentration (3.910m) at a dissolved oxygen of 10% is higher than that reported in the reference.

The method for producing glucosamine by culturing microorganism with a low-cost medium has following advantages over other conventional techniques:

1. The production of glucosamine obtained by the inventive method is higher than that reported in the literature.

2. The cost of the medium for producing glucosamine used in the inventive method is far cheaper than that reported in the literature.

3. The analytical method used in the inventive method is easy to operate, has fewer steps, and is simpler compared with the analytical method used in the literature.

Many changes and modifications in the above described embodiment of the invention can, of course, be carried out without departing from the scope thereof. Accordingly, to promote the progress in science and the useful arts, the invention is disclosed and is intended to be limited only by the scope of the appended claims. 

1. A method for producing glucosamine with a microorganism, comprising fermenting with Monascus pilosus, comprising fermenting a liquid medium with a Monascus pilosus under conditions suitable to produce glucosamine, wherein the liquid medium comprises 25 g/L rice bran, 25 g/L white crystal sugar and 15 g/L NH4Cl.
 2. A method for producing glucosamine with a microorganism as recited in claim 1, wherein the microorganism is fermented under condition of pH 4˜pH
 6. 3. A method for producing glucosamine with a microorganism as recited in claim 1, wherein, after fermentation of the microorganism, the fermentation liquor is filtered with suction to recover the microorganism biomass, and then the microorganism biomass is subjected to steps of cell disruption with a cell disrupter, hydrochloric acid reaction, neutralization reaction and filtration to obtain glucosamine produced by the microorganism.
 4. A method for producing glucosamine with microorganism as recited in claim 3, wherein the hydrochloric acid reaction is carried out with 1 g wet biomass and 6 N HCl at 100° C. for 4 hours to retain a glucosamine concentration approaching a stationary value.
 5. A method for producing glucosamine with microorganism as recited in claim 3, wherein the neutralization reaction is carried out with NaOH to neutralize the reaction solution to pH
 7. 